Field of the Invention
Embodiments of the invention generally relate to processing substrates, such as semiconductor substrates, in lateral flow chambers
Description of the Related Art
Semiconductor substrates are processed for a wide variety of applications, including the fabrication of integrated devices and microdevices. One method of processing substrates includes depositing a material, such as a dielectric material or a conductive metal, on an upper surface of the substrate. The material may be deposited in a lateral flow chamber by flowing a process gas parallel to the surface of a substrate positioned on a support, and thermally decomposing the process gas to deposit a material from the gas onto the substrate surface.
During the deposition process, it is undesirable to allow the process gas to travel below the substrate support, thereby inadvertently depositing on chamber components which are difficult to clean or which will affect process performance. To prevent this “backside” deposition, a non-reactive purge gas is provided from a lower portion of the chamber, beneath the substrate support, and allowed to flow up around the substrate support. The upward flow of the purge gas prevents reactive process gas from entering the lower portion of the chamber. The purge gas is then exhausted from an exhaust port located in an upper portion of the chamber.
The purge gas, although effective at reducing backside deposition, reduces the deposition quality on the upper surface of the substrate. As the purge gas flows upward through the a gap between a chamber wall and the substrate support to prevent process gas from traveling therethrough, the purge gas decreases the flow uniformity of the laterally flowing process gas. The upward-directed purge gas causes a turbulent flow in the laterally flowing process gas. The turbulent flow results in an uneven deposition of material across the surface of the substrate, particularly near the edges of the substrate. The uneven deposition of material on the substrate reduces the quality of the substrate and the final manufactured devices. Often, additional processing, such as chemical mechanical polishing, is required to correct the defects caused by the uneven deposition.
Therefore, there is a need for a method and apparatus for processing substrates in lateral flow chambers while reducing backside deposition and facilitating uniform substrate deposition.